积灰对光伏组件发电性能影响的研究

提出了一种评估积灰对光伏组件发电性能影响的有效方法及其数学模型。该方法通过监测光伏发电效率和光伏组件连续积灰的灰尘密度值,建立了输出功率退化数学模型,从理论上说明光伏组件表面积灰对发电效率的影响,为定量研究灰尘影响发电效率提供了理论支撑。搭建了试验平台进行试验研究,验证了输出功率退化数学模型的精度。     

并网光伏电站关键部件的运行性能分析

简要概述了50kW大型并网光伏电站的系统构成；通过一段时间的运行，对该电站的一些关键部件进行性能评价。分析结果表明：电站的光伏组件设计合理，并网逆变器具有较高的转换效率。     

光伏封装材料对组件性能的影响分析

通过光伏组件不同封装材料和封装方式的常规测试及老化测试对比．讨论了不同材料和不同封装方式对光伏组件性能的影响差异，重点分析了PIB封装密封材料在组件封装中的作用及其对组件的影响。     

光伏组件选型对光伏系统发电量的影响

深入研究了不同种类光伏组件在不同天气条件下的发电特性以及相同种类不同厂家光伏组件的发电特性。实验结果表明不同种类太阳电池在不同季节的发电特性存在明显差异。晶体硅和CIGS(铜铟镓硒)电池冬季发电量明显高于硅薄膜电池,最多可多发电10%左右;随时间推移,三者之间的差异先逐渐减小后增加,到夏季硅薄膜反超多晶硅和CIGS,最多可多发电20%左右。同时,结合光辐照度、温度、湿度等天气资料,测试结果表明:晶体硅和CIGS更适合辐照量高、温度低、湿度小的中国北部地区;硅薄膜在辐照度不高、温度高、湿度大的中国南部大部分地区具有更高发电量。     

基于户外并网光伏电站运行数据的双面光伏组件发电性能研究

在湖南省湘潭地区某建筑屋顶建设光伏电站实证平台，跟踪分析了该平台中户外并网光伏电站在2020年10月—2021年9月这1年间的运行实证数据。总结了光伏电站所在地的气候情况及实测的太阳辐照情况，有针对性地对比了传统单面光伏组件与不同类型双面光伏组件的发电表现，分析了采用不同类型跟踪支架系统的双面光伏组件的发电量增益情况。相关结果可为光伏产品选型和当地光伏发电系统设计提供有效的数据支撑。     

多旋翼清洗无人机在屋顶类分布式光伏电站的应用研究

分布式光伏电站多建设在建筑物屋顶等高处，人工巡检和清洗比较困难，存在劳动力成本大、安全风险高等问题。对多旋翼清洗无人机清洗技术的研究现状进行了分析，研究了可用于建筑物屋顶、车棚顶棚等屋顶类分布式光伏电站光伏组件清洗作业的多旋翼清洗无人机的关键技术，并对此类清洗无人机的应用进行了列举与前景展望。研究结果显示：对于1 MW屋顶类分布式光伏电站的清洗任务，多旋翼清洗无人机的清洗效率是人工清洗的40多倍，耗水量只有人工清洗的1/10，成本仅是人工清洗的1/3左右，除尘率超过90%，具有得天独厚的清洗优势，是解决屋顶类分布式光伏电站运维难题的有效手段，应用前景良好。     

反光材料对采用双面光伏组件的屋顶光伏电站发电性能的影响分析全文替换

通过搭建实证系统,研究了2种防水卷材和3种白漆对双面光伏组件发电量的影响,为工商业屋顶光伏电站采用双面光伏组件的设计提供了理论支持;并将各种材料的成本和电站发电量收益情况进行了对比分析,获得了较为优化的解决方案。     

积灰对光伏发电的影响及除尘效果实验研究

通过对兰州地区的灰尘沉降情况及积灰影响光伏组件发电效率进行实验研究,结果表明,在秋季无降雨情况下,当积灰密度达到2.068 g/m2时,输出电流下降约22.6%,平均每天下降1.51%。同时以某地38 kW分布式光伏电站为背景,分析水射流清洗方式的清灰效益及除尘率,发现清洗后除尘率可达86.3%,平均每天可多发电6.25 kWh。并对课题组自行研制的光伏电站干式清灰设备清灰效果进行验证,发现该设备除尘率最高可达95.3%,可满足中国西北地区大型光伏电站的清灰作业要求。     

光伏电站旁路二极管应用失效分析

主要研究光伏电站中经常出现的集中区域多接线盒二极管失效、零星接线盒内部二极管全部失效、正反偏置电压对二极管的性能影响、ESD静电能力对二极管性能的影响,以及正常发电光伏组件出现热斑等异常现象时旁路二极管的工作状态。通过相关探索性试验,进一步破析二极管从失效初期到最终失效的发展过程和因素,以便确定电站在不同工作状态下对二极管工作可靠性的要求,并在此基础上作出总结。     

西安城区灰尘对分布式光伏电站输出功率的影响分析

根据光伏组件输出易受积灰影响的特点,分析了城区灰尘对分布式光伏电站的影响。并在西安城区某分布式光伏电站中设计对比实验,实验表明在"降尘"天气影响下,城区灰尘对光伏系统输出功率降低影响很大,在本实验中达到15%。     

Thermal performance of a novel rooftop solar micro-concentrating collector

Concentrating solar thermal systems offer a promising method for large scale solar energy collection. Although concentrating collectors are generally thought of as large-scale stand-alone systems, there is a huge opportunity to use novel concentrating solar thermal systems for rooftop applications such as domestic hot water, industrial process heat and solar air conditioning for commercial, industrial and institutional buildings. This paper describes the thermal performance of a new low-cost solar thermal micro-concentrating collector (MCT), which uses linear Fresnel reflectors, and is designed to operate at temperatures up to 220 °C. The modules of this collector system are approximately 3 m long by 1 m wide and 0.3 m high. The objective of the study is to optimise the design to maximise the overall thermal efficiency. The absorber is contained in a sealed enclosure to minimise convective losses. The main heat losses are due to natural convection inside the enclosure and radiation heat transfer from the absorber tube. In this paper we present the results of a computational and experimental investigation of radiation and convection heat transfer in order to understand the heat loss mechanisms. A computational model for the prototype collector has been developed using ANSYS–CFX, a commercial computational fluid dynamics software package. The numerical results are compared to experimental measurements of the heat loss from the absorber, and flow visualisation within the cavity. This paper also presents new correlations for the Nusselt number as a function of Rayleigh number.     

Aeolian dust deposition on photovoltaic solar cells: the effects of wind velocity and airborne dust concentration on cell performance

Wind tunnel experiments were conducted to investigate the effect of wind velocity and airborne dust concentration on the drop of photovoltaic (PV) cell performance caused by dust accumulation on such cells. Performance drop was investigated at four wind velocities and four dust concentrations. I–V characteristics were determined for various intensities of cell pollution. The evolutions of the short circuit current, the open circuit voltage, the maximum power, the reduction of solar intensity received by the cells, and the fill factor variation with increasing cell pollution were examined. The deposition (and accumulation) of fine aeolian dust on PV cells significantly affects the performance of such cells. Wind velocity has an important impact on cell performance drop, since the drop is larger in high winds than in low winds. However, the wind also affects the sedimentological structure of the dust coating on the cell, resulting in a higher transmittance (of light) for coatings created during high winds. The wind tunnel experiments indicate that the former effect is more important than the latter, which means that, in general, the drop in PV cell performance due to dust accumulation is larger as wind speed increases. Airborne dust concentration also affects the drop in PV cell performance, since high dust concentrations lead to a higher accumulation on the cell. Contrary to wind speed, airborne dust concentration does not seem to affect the sedimentological structure of dust coatings (with respect to light transmittance) on PV cells.     

Effect of dust deposition on the performance of a solar desalination plant operating in an arid desert area

The performance of a solar desalination plant (whether using thermal or photovoltaic collectors) is influenced by the ability of the glazing system to transmit solar radiation to the collector absorption surface. This ability is influenced by such factors as the intensity of solar radiation, the transmittance of the collector glazing, the tilt angle of the absorbing surface, the operating parameters of the plant, the properties of the materials of construction, etc. This paper discusses the influence of dust deposition on the evacuated tube collector field on the operating performance of the solar desalination plant at Abu Dhabi, UAE. This plant has a collector field area of 1864 m² of absorber surface and an MED (multiple effect distillation) unit for seawater desalination with a capacity of 120 m³/day of distilled water. The reduction in transmittance due to dust deposition on the amount of heat collected has been measured and its influence on the distillate production has been estimated using the computer simulation program SOLDES which has been verified previously as an effective tool for predicting the operating performance of similar plant designs. The frequency of high-pressure water jet cleaning on the performance of the plant was also investigated. It was found that dust deposition and its effect on plant performance depend strongly on the season of the year and the frequency of jet cleaning should be adjusted accordingly.     

Hydrogen as a battery for a rooftop household solar power generation unit

Decentralization of electrical power generation using rooftop solar units is projected to develop to not only mitigate power losses along transmission and distribution lines, but to control greenhouse gases emissions. Due to intermittency of solar energy, traditional batteries are used to store energy. However, batteries have several drawbacks such as limited lifespan, low storage capacity, uncontrolled discharge when not connected to a load and limited number of charge/discharge cycles. In this paper, the feasibility of using hydrogen as a battery is analyzed where hydrogen is produced by the extra diurnal generated electricity by a rooftop household solar power generation unit and utilized in a fuel cell system to generate the required electrical power at night. In the proposed design, two rooftop concentrated photovoltaic thermal (CPVT) systems coupled with an organic Rankine cycle (ORC) are used to generate electricity during 9.5 h per day and the extra power is utilized in an electrolyzer to produce hydrogen. Various working fluids (Isobutane, R134a, R245fa and R123) are used in the ORC system to analyze the maximum feasible power generation by this section. Under the operating conditions, the generated power by ORC as well as its efficiency are evaluated for various working fluids and the most efficient working fluid is selected. The required power for the compressor in the hydrogen storage process is calculated and the number of electrolyzer cells required for the hydrogen production system is determined. The results indicate that the hybrid CPVT-ORC system produces 2.378 kW of electricity at 160 suns. Supplying 65% of the produced electricity to an electrolyzer, 0.2606 kg of hydrogen is produced and stored for nightly use in a fuel cell system. This amount of hydrogen can generate the required electrical power at night while the efficiency of electrolyzer is more than 70%.     

Recommendations for the market introduction of solar thermal power stations

Until 2010, solar thermal power stations based on parabolic trough concentrating collectors can become a competitive option on the world's electricity market, if the market extension of this mature technology is supported by a concerted, long-term programme capable of bundling the forces of industry, finance, insurance and politics. Technical improvements based on the experience of over ten years of successful operation, series production and economies of scale will lead to a further cost reduction of 50% and to electricity costs of 0.06 - 0.04 US$/kWh for hybrid steam cycles and hybrid combined cycles, respectively. Until 2010, a capacity of 7 GW will be installed, avoiding 16 million tons of carbon dioxide per year. The programme comprises an investment of 16 billion US$ and requires external funding of 6%.     

Influence of an ammonia activation prior to the PECVD SiN deposition on the solar cell performance

Silicon nitride (SiN) from plasma-enhanced chemical vapour deposition is widely used in PV industry as an antireflection coating. In addition the large amount of hydrogen (of up to 25 at%) (J. Appl. Phys. 49 (1978) 2473) incorporated in the SiN layer can be driven into the solar cell during the contact firing step, leading to an excellent bulk passivation as demonstrated by several research institutes during the last decade (Proceedings of the 12th EC PVSEC, Amsterdam, The Netherlands, 1994, p. 1018). Despite these advantages sometimes a problem occurs during the firing of the SiN layer, called blistering. Supposing that the blistering effect can be influenced by the surface preparation we performed a short ammonia plasma activation step prior to the SiN deposition. This step results in no damage of the surface which is shown in the form of solar cell results and lifetime measurements. On the contrary a positive effect on lowly doped emitters is possible.     

Steady-state performance of a grid-connected rooftop hybridwind-photovoltaic power system with battery storage

This paper reports the performance of a 4-kW grid-connected residential wind-photovoltaic system (WPS) with battery storage located in Lowell, MA, USA. The system was originally designed to meet a typical New-England (TNE) load demand with a loss of power supply probability (LPSP) of one day in ten years as recommended by the Utility Company. The data used in the calculation was wind speed and irradiance of Login Airport Boston (LAB) obtained from the National Climate Center in North Carolina. The present performance study is based on two-year operation. (May 1996-Apr 1998) of the WPS. Unlike conventional generation, the wind and the sunrays are available at no cost and generate electricity pollution-free. Around noontime the WPS satisfies its load and provides additional energy to the storage or to the grid. On-site energy production is undoubtedly accompanied with minimization of environmental pollution, reduction of losses in power systems transmission and distribution equipment, and supports the utility in demand side management. This paper includes discussion on system reliability, power quality, loss of supply and effects of the randomness of the wind and the solar radiation on system design     

Experimental study on the effect of dust deposition on solar photovoltaic panels in desert environment

The accumulation of dust particles deteriorates the performance of solar cells and results in appreciable losses in the generated power due to the sun irradiance scattering effects on the surface of the solar panel. This study investigates the impact of dust accumulation on photovoltaic solar modules in Baghdad city in Iraq. For this purpose an experiment has been conducted to quantify losses caused by the accumulation of dust on the surface of three identical photovoltaic solar modules. The modules have been installed with direct exposure to weather conditions, in a well controlled experimental setup. Subsequently, measurements of dust accumulation on modules have been taken on daily, weekly and monthly basis. The dust density and size distribution of aerosol particles and fibers have been also investigated and measured by a highly sensitive aerosols measuring system. The dusted module and another similar clean module have been then exposed to constant radiation and constant temperature using a solar simulator as light source. The deposition of the dust on the surface of the photovoltaic solar modules showed a reduction in both the short circuit current (I_sc) and the output power compared to the same parameters of the clean module. The average degradation rate of the efficiencies of the solar modules exposed to dust are; 6.24%, 11.8% and 18.74% calculated for exposure periods of one day, one week and one month. The experimental results are well compared with the calculations obtained by a theoretical model recently developed by the authors.     

Business models and financing options for a rapid scale-up of rooftop solar power systems in Thailand

Diverse solar PV business models and financing options exist in the international landscape, helping expand and accelerate the adoption of rooftop solar PV systems. The conditions for their emergence are context specific, depending on the policies, regulations, incentives, and market conditions of each country. After a review of the international landscape, this paper compiles and analyzes business models and financing options for rooftop solar PV investment in Thailand that have emerged during the period between 2013 and 2015. Despite policy discontinuity for the support of rooftop solar systems, diverse business models and financing options are driving market expansion and expanding solar access to more Thai consumers. Drawing on our policy and regulatory analyses and in-depth interviews with business representatives, we identify four types of business models and one financing option. The business models include Roof Rental, Solar PPA, Solar Leasing, and Community Solar, and the financing option is the solar loan. We analyze the drivers for their emergence, barriers to their success, and the risks from the business owners' and consumers' viewpoints. Our policy recommendation is focused on crafting a net-metering regulation with evidence-based studies on the potential costs and benefits to different stakeholders.     

集热棚高度对太阳能热气流发电性能的影响

以内蒙古乌海金沙湾太阳能烟囱热气流发电站为研究对象,应用ANSYS-Fluent软件对电站系统进行了稳态数值计算,模拟不同集热棚高度下系统内部流场和压力场的分布规律。模拟结果的对比分析显示,对该电站而言,集热棚高度以6⁸ m为宜。